No wonder Schwan began hankering for virtualization-layer security years ago.

When Schwan began its virtualization implementation, it decided to run VMware's ESX on bare-metal hardware rather than selecting a hypervisor that would sit atop a Windows or Linux operating system.

That was a way to avoid having to worry about operating system patches or security flaws affecting the hypervisor, Miller says. "Still, initially, we used our virtualization for a lot of transactional data but not for credit-card processing or other sensitive data," he adds.

By 2005, Schwan felt comfortable moving sensitive data into the virtual environment. It used traditional physical firewalls to mask, protect and segregate user environments across the development, staging, quality assurance and production networks, Miller says.

But it didn't take long before problems appeared.

"I could put different kinds of sensitive data – credit card or HIPAA, say – on the same systems and lock them down because we followed the same processes, auditing and compliance for them. But I didn't want to put a SharePoint server on the same host that was processing credit cards," he says. "I could track the data going host to host, but I didn't have the control, monitoring or capabilities to see what was going on within a host."

Addressing that situation meant carving hosts out of the resource pool and creating lockbox environments for sensitive data. And that, in turn, meant Schwan wasn't getting enough throughput or efficiency out of its hosts, Miller says.

So Schwan immediately began looking for a virtual firewall that could sit at the virtualization layer and do the segregation. It selected vTrust Security from Reflex System, at the time one of the only companies offering a virtual firewall, Miller says.

Schwan can still segment sensitive environments, but now Miller does so out of the entire host pool rather than carving off sections of it, he explains. The virtual firewall inspects traffic on a host and blocks its movement from one guest machine to another.

This gives Schwan the ability to run virtual desktops with greater peace of mind, for example. "We might have some executive or high-risk virtual desktops that we keep track of through user monitoring or auditing. We don't want a plant user on the other side of the world being able to get to that person's desktop. Now those virtual desktops can sit on the same hosts and I don't have to worry about the potential for interaction," Miller says.

In its implementation, Schwan was careful to create the same types of firewall rules as it has for the physical firewalls and personal firewalls running on user desktops, Miller says. "That way, guests running on a host are protected within the host and as soon as they exit the virtual switch because they'll move directly into the segmentation created by the physical firewall using the same rule sets," he explains.

This also facilitates auditing. As virtual machines are moved from host to host through VMware's VMotion technology, they get dropped into the same type of firewall environment or segregated subnet as needed. "By taking a virtual firewall and being able to release those rules so they go across the entire set of hosts within that pool," Miller says, "I'm protected wherever that guest goes."